Ambiguities in MR imaging of tumoral cysts in the spinal cord.

We describe two cases in which the magnetic resonance (MR) imaging characteristics of tumors of the spinal cord were ambiguous. Both cases were primary low-grade astrocytomas that had had previous surgery. In the first case the findings were indeterminate as to whether the lesion was solid, cystic with proteinaceous fluid, or mixed. Intraoperative ultrasound demonstrated large cystic areas with an associated solid mass. In the second case MR was reported as cystic with a solid nodule. Ultrasonography demonstrated an almost entirely solid mass with a localized cyst corresponding to the presumed solid area. In both of these cases, but especially the latter, the localization of cysts within the lesions was of vital importance to therapy.